Background: Different superparamagnetic iron oxide nanoparticles have been tested for their potential use in cancer treatment, as they enter into cells with high effectiveness, do not induce cytotoxicity, and are retained for relatively long periods of time inside the cells. We have analyzed the interaction, internalization and biocompatibility of dimercaptosuccinic acid-coated superparamagnetic iron oxide nanoparticles with an average diameter of 15 nm and negative surface charge in MCF-7 breast cancer cells.

Conclusions: All these findings indicate that dimercaptosuccinic acid-coated superparamagnetic iron oxide nanoparticles have excellent properties in terms of efficiency and biocompatibility for application to target breast cancer cells.

Mentions:
To identify the precise mechanism of endocytosis (phagocytosis, pinocytosis, macropinocytosis, clathrin- mediated endocytosis, or caveolae-mediated endocytosis), we performed transmission electron microscopy (TEM) studies. The high contrast of the magnetic particles allowed for their clear identification (Figure 4). Small groups of particles were seen near cell membranes. Actually, SPION incubated in culture media present a relatively wide size distribution (ranging between 50 to more than 400 nm, see Additional file 2). Although we did not make an attempt to sort the SPION by size, we found significant differences in the way the SPION were incorporated in the cells according to the aggregate size. Smaller aggregates were seen adjacent to distinct clathrin-coated patches (Figure 4A). Closed clathrin vesicles containing small DMSA-SPION aggregates (smaller than 200 nm) were seen in the cytoplasm, near membrane. Larger DMSA-SPION aggregates were seen near cell periphery, in most cases engulfed by cell membrane extensions, indicating the existence of a macropinocytic DMSA-SPION uptake process (Figure 4B a, b). Other studies have also proposed a macropinocytic process for cationic iron oxide nanoparticles internalization [30], as well as for other nanoparticles [31].Figure 4

Mentions:
To identify the precise mechanism of endocytosis (phagocytosis, pinocytosis, macropinocytosis, clathrin- mediated endocytosis, or caveolae-mediated endocytosis), we performed transmission electron microscopy (TEM) studies. The high contrast of the magnetic particles allowed for their clear identification (Figure 4). Small groups of particles were seen near cell membranes. Actually, SPION incubated in culture media present a relatively wide size distribution (ranging between 50 to more than 400 nm, see Additional file 2). Although we did not make an attempt to sort the SPION by size, we found significant differences in the way the SPION were incorporated in the cells according to the aggregate size. Smaller aggregates were seen adjacent to distinct clathrin-coated patches (Figure 4A). Closed clathrin vesicles containing small DMSA-SPION aggregates (smaller than 200 nm) were seen in the cytoplasm, near membrane. Larger DMSA-SPION aggregates were seen near cell periphery, in most cases engulfed by cell membrane extensions, indicating the existence of a macropinocytic DMSA-SPION uptake process (Figure 4B a, b). Other studies have also proposed a macropinocytic process for cationic iron oxide nanoparticles internalization [30], as well as for other nanoparticles [31].Figure 4

Background: Different superparamagnetic iron oxide nanoparticles have been tested for their potential use in cancer treatment, as they enter into cells with high effectiveness, do not induce cytotoxicity, and are retained for relatively long periods of time inside the cells. We have analyzed the interaction, internalization and biocompatibility of dimercaptosuccinic acid-coated superparamagnetic iron oxide nanoparticles with an average diameter of 15 nm and negative surface charge in MCF-7 breast cancer cells.

Conclusions: All these findings indicate that dimercaptosuccinic acid-coated superparamagnetic iron oxide nanoparticles have excellent properties in terms of efficiency and biocompatibility for application to target breast cancer cells.